[PATCH net-next v3 1/2] openvswitch: allow specifying ifindex of new interfaces

[Andrey Zhadchenko <andrey.zhadchenko@virtuozzo.com>]

CRIU is preserving ifindexes of net devices after restoration. However,
current Open vSwitch API does not allow to target ifindex, so we cannot
correctly restore OVS configuration.

Add new OVS_DP_ATTR_IFINDEX for OVS_DP_CMD_NEW and use it as desired
ifindex.
Use OVS_VPORT_ATTR_IFINDEX during OVS_VPORT_CMD_NEW to specify new netdev
ifindex.

Signed-off-by: Andrey Zhadchenko <andrey.zhadchenko@virtuozzo.com>
---

v3:
Added new OVS_DP_ATTR_IFINDEX instead of using ovs_header->dp_ifindex to
ensure we won't break existing software
Removed unnecessary OVS_VPORT_TYPE_INTERNAL check
Moved desired_ifindex in struct vport_parms for better padding.
Added some documentation

 include/uapi/linux/openvswitch.h     |  3 +++
 net/openvswitch/datapath.c           | 11 +++++++++--
 net/openvswitch/vport-internal_dev.c |  1 +
 net/openvswitch/vport.h              |  2 ++
 4 files changed, 15 insertions(+), 2 deletions(-)

diff --git a/include/uapi/linux/openvswitch.h b/include/uapi/linux/openvswitch.h
index ce3e1738d427..94066f87e9ee 100644
--- a/include/uapi/linux/openvswitch.h
+++ b/include/uapi/linux/openvswitch.h
@@ -76,6 +76,8 @@ enum ovs_datapath_cmd {
  * datapath.  Always present in notifications.
  * @OVS_DP_ATTR_MEGAFLOW_STATS: Statistics about mega flow masks usage for the
  * datapath. Always present in notifications.
+ * @OVS_DP_ATTR_IFINDEX: Interface index for a new datapath netdev. Only
+ * valid for %OVS_DP_CMD_NEW requests.
  *
  * These attributes follow the &struct ovs_header within the Generic Netlink
  * payload for %OVS_DP_* commands.
@@ -92,6 +94,7 @@ enum ovs_datapath_attr {
 	OVS_DP_ATTR_PER_CPU_PIDS,   /* Netlink PIDS to receive upcalls in
 				     * per-cpu dispatch mode
 				     */
+	OVS_DP_ATTR_IFINDEX,
 	__OVS_DP_ATTR_MAX
 };
 
diff --git a/net/openvswitch/datapath.c b/net/openvswitch/datapath.c
index 7e8a39a35627..2ca86b53c032 100644
--- a/net/openvswitch/datapath.c
+++ b/net/openvswitch/datapath.c
@@ -1779,6 +1779,8 @@ static int ovs_dp_cmd_new(struct sk_buff *skb, struct genl_info *info)
 	parms.dp = dp;
 	parms.port_no = OVSP_LOCAL;
 	parms.upcall_portids = a[OVS_DP_ATTR_UPCALL_PID];
+	parms.desired_ifindex = a[OVS_DP_ATTR_IFINDEX]
+		? nla_get_u32(a[OVS_DP_ATTR_IFINDEX]) : 0;
 
 	/* So far only local changes have been made, now need the lock. */
 	ovs_lock();
@@ -1996,6 +1998,7 @@ static const struct nla_policy datapath_policy[OVS_DP_ATTR_MAX + 1] = {
 	[OVS_DP_ATTR_USER_FEATURES] = { .type = NLA_U32 },
 	[OVS_DP_ATTR_MASKS_CACHE_SIZE] =  NLA_POLICY_RANGE(NLA_U32, 0,
 		PCPU_MIN_UNIT_SIZE / sizeof(struct mask_cache_entry)),
+	[OVS_DP_ATTR_IFINDEX] = {.type = NLA_U32 },
 };
 
 static const struct genl_small_ops dp_datapath_genl_ops[] = {
@@ -2199,7 +2202,10 @@ static int ovs_vport_cmd_new(struct sk_buff *skb, struct genl_info *info)
 	if (!a[OVS_VPORT_ATTR_NAME] || !a[OVS_VPORT_ATTR_TYPE] ||
 	    !a[OVS_VPORT_ATTR_UPCALL_PID])
 		return -EINVAL;
-	if (a[OVS_VPORT_ATTR_IFINDEX])
+
+	parms.type = nla_get_u32(a[OVS_VPORT_ATTR_TYPE]);
+
+	if (a[OVS_VPORT_ATTR_IFINDEX] && parms.type != OVS_VPORT_TYPE_INTERNAL)
 		return -EOPNOTSUPP;
 
 	port_no = a[OVS_VPORT_ATTR_PORT_NO]
@@ -2236,11 +2242,12 @@ static int ovs_vport_cmd_new(struct sk_buff *skb, struct genl_info *info)
 	}
 
 	parms.name = nla_data(a[OVS_VPORT_ATTR_NAME]);
-	parms.type = nla_get_u32(a[OVS_VPORT_ATTR_TYPE]);
 	parms.options = a[OVS_VPORT_ATTR_OPTIONS];
 	parms.dp = dp;
 	parms.port_no = port_no;
 	parms.upcall_portids = a[OVS_VPORT_ATTR_UPCALL_PID];
+	parms.desired_ifindex = a[OVS_VPORT_ATTR_IFINDEX]
+		? nla_get_u32(a[OVS_VPORT_ATTR_IFINDEX]) : 0;
 
 	vport = new_vport(&parms);
 	err = PTR_ERR(vport);
diff --git a/net/openvswitch/vport-internal_dev.c b/net/openvswitch/vport-internal_dev.c
index 5b2ee9c1c00b..f0059b7243df 100644
--- a/net/openvswitch/vport-internal_dev.c
+++ b/net/openvswitch/vport-internal_dev.c
@@ -147,6 +147,7 @@ static struct vport *internal_dev_create(const struct vport_parms *parms)
 	}
 
 	dev_net_set(vport->dev, ovs_dp_get_net(vport->dp));
+	dev->ifindex = parms->desired_ifindex;
 	internal_dev = internal_dev_priv(vport->dev);
 	internal_dev->vport = vport;
 
diff --git a/net/openvswitch/vport.h b/net/openvswitch/vport.h
index 9de5030d9801..7d276f60c000 100644
--- a/net/openvswitch/vport.h
+++ b/net/openvswitch/vport.h
@@ -90,12 +90,14 @@ struct vport {
  * @type: New vport's type.
  * @options: %OVS_VPORT_ATTR_OPTIONS attribute from Netlink message, %NULL if
  * none was supplied.
+ * @desired_ifindex: New vport's ifindex.
  * @dp: New vport's datapath.
  * @port_no: New vport's port number.
  */
 struct vport_parms {
 	const char *name;
 	enum ovs_vport_type type;
+	int desired_ifindex;
 	struct nlattr *options;
 
 	/* For ovs_vport_alloc(). */
-- 
2.31.1